A way to obtain a wide-viewing-angle liquid crystal display panel is to adopt an in-plane switching mode. In the in-plane switching mode, switching is performed such that liquid crystal molecules are kept horizontal with respect to a substrate, and since the liquid crystal molecules are prevented from getting slanted, optical characteristics are hardly to be affected by viewing angle, and thus it is possible to obtain a wide viewing angle. See patent documents 1 and 2 for examples of the liquid crystal display panel adopting the in-plane switching mode.
In the liquid crystal display panel adopting the in-plane switching mode, when a high potential, such as high voltage caused by static electricity, is applied from the outside, display is disadvantageously disturbed by charging. In order to solve this problem, patent document 2 proposes that a conductive layer having translucency is formed on one of the transparent substrates in the liquid crystal display panel, the one disposed on the opposite side to a liquid crystal layer, namely a CF glass substrate, on a surface thereof at a far side from a backlight unit.
In the liquid crystal display panel adopting the in-plane switching mode, when in order to prevent static charge, a conductive film is provided that covers the upper surface of the CF glass substrate or the upper surface of a polarization plate overlaid on the CF glass substrate, the conductive film needs to be grounded. Patent document 2 also discloses various grounding methods. An example of conventional grounding method is shown in FIGS. 10 and 11.
The liquid crystal display panel 1 adopting the in-plane switching mode shown in FIG. 10 has a cross-sectional structure shown in FIG. 11. Specifically, on the upper surface of a thin film transistor (hereinafter abbreviated as a “TFT”) glass substrate 10, a color filter (hereinafter abbreviated as a “CF”) glass substrate 11 is overlaid. A liquid crystal layer (not shown) is sealed in between the TFT glass substrate 10 and the CF glass substrate 11. A transparent conductive film 12 is formed so as to cover the upper surface of the CF glass substrate 11. The conductive film 12 covers the entire display region of the liquid crystal display panel 1. A polarization plate 13 is overlaid on the conductive film 12.
The dimension of the TFT glass substrate 10 in the vertical direction of in FIG. 10 is greater than that of the CF glass substrate 11, and a part of the TFT glass substrate 10 protrudes from the CF glass substrate 11. The protruding part forms an external connection region 14. A driver 15 of the liquid crystal display panel 1 is arranged on the external connection region 14, and also a ground electrode 16 for grounding is formed on the external connection region 14.
An electrical connection between the conductive film 12 and the ground electrode 16 is established in the following manner. A conductive paste 17 is adhered to a portion crossing a border between the conductive film 12 and the ground electrode 16. The conductive paste 17 forms the electrical connection. Then, the conductive paste 17 is heated, thereby a solvent is evaporated from the conductive paste 17 and the conductive paste 17 is cured. As the conductive paste 17, for example, a silver paste is used.
As shown in FIG. 12, it is possible for the conductive film 12 to cover the upper surface of the polarization plate 13 instead of CF glass substrate 11. In this case, the conductive paste 17 that is adhered to the portion crossing the border between the conductive film 12 and the ground electrode 16 is inevitably in contact with the CF glass substrate 11 halfway the span of the conductive paste 17.